CLAB is a collection of functions for performing cluster analysis and related activities. The CLAB functions are operators embedded in the MLAB (Modelin, LABoratory) system, a modeling language originally developed at NIH for use on DEC-10 and DEC-20 computers. The MLAB system is widely used by medical researchers, scientists, and statisticians. Many MLAB users find CLAB of occasional use, and some find CLAB to be of primary interest. MLAB is currently being converted for use on PC/AT personal computers under the PC-DOS operating system. However, this conversion does not include the CLAB operators. One aim of this proposal are is to convert the existing CLAB algorithms and integrate them into PC-MLAB, with enhancements suitable to the AT/DOS environment. The resulting system will serve the needs of MLAB users as DEC-10s and -20s are phased out. It will also be available for new users who have not had access to MLAB/CLAB. Another aim is to study extensions the CLAB system to optimally serve classes of new users. Such classes include systematic biologists and researchers using flow cytometry. The latter is particularly of note, due to the importance of flow cytometry in diagnosis of leukemia and AIDS.